The present invention relates to inhibitors of the nuclear enzyme poly(adenosine 5′-diphospho-ribose) polymerase [“poly(ADP-ribose) polymerase” or “PARP”, which is also referred to as ADPRT (NAD:protein (ADP-ribosyl transferase (polymerising)) and PARS (poly(ADP-ribose) synthetase) and provides compounds and compositions containing the disclosed compounds. Moreover, the present invention provides methods of using the disclosed PARP inhibitors to treat cancer.
There is considerable interest in the development of PARP inhibitors as chemosensitizers for use in cancer therapy and to limit cellular damage after ischemia or endotoxic stress. In particular, potentiation of temozolomide cytotoxicity observed in preclinical studies with potent PARP-1 inhibitors reflects inhibition of base excision repair and subsequent cytotoxicity due to incomplete processing of N7-methylguanine and N3-methyladenine. There is now a body of preclinical data demonstrating that the cytotoxicity of temozolomide is potentiated by coadministration of a PARP inhibitor either in vitro or in vivo. Plummer, et al., Clin. Cancer Res., 11(9), 3402 (2005).
Temozolomide, a DNA methylating agent, induces DNA damage, which is repaired by O6-alkylguanine alkyltransferase (ATase) and poly(ADP-ribose) polymerase-1 (PARP-1)-dependent base excision repair. Temozolomide is an orally available monofunctional DNA alkylating agent used to treat gliomas and malignant melanoma. Temozolomide is rapidly absorbed and undergoes spontaneous breakdown to form the active monomethyl triazene, 5-(3-methyl-1-triazeno)imidazole-4-carboxamide. Monomethyl triazene forms several DNA methylation products, the predominate species being N7-methylguanine (70%), N3-methyladenine (9%), and O6-methylguanine (5%). Unless repaired by O6-alkylguanine alkyltransferase, O6-methylguanine is cytotoxic due to mispairing with thymine during DNA replication. This mispairing is recognized on the daughter strand by mismatch repair proteins and the thymine excised. However, unless the original O6-methylguanine nucleotide in the parent strand is repaired by ATase-mediated removal of the methyl adduct, thymine can be reinserted. Repetitive futile rounds of thymine excision and incorporation opposite an unrepaired O6-methylguanine nucleotide causes a state of persistent strand breakage and the MutS branch of mismatch repair system signals G2-M cell cycle arrest and the initiation of apoptosis. The quantitatively more important N7-methylguanine and N3-methyladenine nucleotide alkylation products formed by temozoloride are rapidly repaired by base excision repair. Plummer, et al., Clin. Cancer Res., 11(9), 3402 (2005).
Chemosensitization by PARP inhibitors is not limited to temozolomide. Cytotoxic drugs, generally, or radiation can induce activation of PARP-1, and it has been demonstrated that inhibitors of PARP-1 can potentiate the DNA damaging and cytotoxic effects of chemotherapy and irradiation. Kock, et al., 45 J Med. Chem. 4961 (2002). PARP-1 mediated DNA repair in response to DNA damaging agents represents a mechanism for drug resistance in tumors, and inhibition of this enzyme has been shown to enhance the activity of ionizing radiation and several cytotoxic antitumor agents, including temozolomide and topotecan. Suto et al, in U.S. Pat. No. 5,177,075, disclose several isoquinolines used for enhancing the lethal effects of ionizing radiation or chemotherapeutic agents on tumor cells. Weltin et al., “Effect of 6(5H)-Phenanthridinone, an Inhibitor of Poly(ADP-ribose) Polymerase, on Cultured Tumor Cells”, Oncol Res., 6:9, 399-403 (1994) disclose the inhibition of PARP activity, reduced proliferation of tumor cells, and a marked synergistic effect when tumor cells are co-treated with an alkylating drug. PARP-1 is thus a potentially important therapeutic target for enhancing DNA-damaging cancer therapies.
PARP inhibitors can also inhibit the growth of cells having defects in the homologous recombination (HR) pathway of double-stranded DNA repair. See Bryant et al., “Specific killing of BRCA2-deficient tumours with inhibitors of poly(ADP-ribose) polymerase,” Nature 434, 913 (2005); Farmer et al., “Targeting the DNA repair defect in BRCA mutant cells as a therapeutic strategy,” Nature 434, 917 (2005). This effect operates without the presence of chemosensitizers. Id. Known states associated with HR defects include BRCA-1 defects, BRCA-2 defects, and Fanconi anemia-associated cancers. McCabe et al., “Deficiency in the Repair of DNA Damage by Homologous Recombination and Sensitivity to Poly(ADP-Ribose) Polymerase Inhibition,” Cancer Res. 66. 8109 (2006). Proteins identified as associated with a Fanconi anemia include FANCA, FANCB, FANCC, FANCD2, FANCE, FANCF, FANCG, FANCL, and FANCM. Id. For reviews, see Zaremba et al., “PARP Inhibitor Development for Systemic Cancer Targeting,” Anti-Cancer Agents in Medicinal Chemistry 7, 515 (2007) and Lewis et al., “Clinical poly(ADP-ribose) polymerase inhibitors for the treatment of cancer,” Curr Opin. Investigational Drugs 8, 1061 (2007).
Large numbers of known PARP inhibitors have been described in Banasik et al., “Specific Inhibitors of Poly(ADP-Ribose) Synthetase and Mono(ADP-Ribosyl)-Transferase”, J. Biol. Chem., 267:3, 1569-75 (1992), and in Banasik et al., “Inhibitors and Activators of ADP-Ribosylation Reactions”, Molec. Cell. Biochem., 138, 185-97 (1994). However, effective use of these PARP inhibitors, in the ways discussed above, has been limited by the concurrent production of unwanted side-effects. See Milam et al., “Inhibitors of Poly(Adenosine Diphosphate-Ribose) Synthesis; Effect on Other Metabolic Processes,” Science, 223, 589-91 (1984).
In addition to the above, PARP inhibitors have been disclosed and described in the following international patent applications: WO 00/42040; WO 00/39070; WO 00/39104; WO 99/11623; WO 99/11628; WO 99/11622; WO 99/59975; WO 99/11644; WO 99/11945; WO 99/11649; and WO 99/59973. A comprehensive review of the state of the art has been published by Li and Zhang in IDrugs 2001, 4(7): 804-812 (PharmaPress Ltd ISSN 1369-7056).
The ability of PARP-inhibitors to potentiate the lethality of cytotoxic agents by chemosensitizing tumor cells to the cytotoxic effects of chemotherapeutic agents has been reported in, inter alia, US 2002/0028815; US 2003/0134843; US 2004/0067949; White A W, et al., 14 Bioorg. and Med. Chem. Letts. 2433 (2004); Canon Koch S S, et al., 45 J. Med. Chem. 4961 (2002); Skalitsky D J, et al., 46 J. Med. Chem. 210 (2003); Farmer H, et al., 434 Nature 917 (14 Apr. 2005); Plummer E R, et al., 11(9) Clin. Cancer Res. 3402 (2005); Tikhe J G, et al., 47 J. Med. Chem. 5467 (2004); Griffin R. J., et al., WO 98/33802; and Helleday T, et al, WO 2005/012305.
The induction of peripheral neuropathy is a common factor in limiting therapy with chemotherapeutic drugs. Quasthoff and Hartung, J. Neurology, 249, 9-17 (2002). Chemotherapy induced neuropathy is a side-effect encountered following the use of many of the conventional (e.g., Taxol, vincritine, cisplatin) and newer chemotherapies (e.g. velcade, epothilone). Depending on the substance used, a pure sensory and painful neuropathy (with cisplatin, oxaliplatin, carboplatin) or a mixed sensorimotor neuropathy with or without involvement of the autonomic nervous system (with vincristine, taxol, suramin) can ensue. Neurotoxicity depends on the total cumulative dose and the type of drug used. In individual cases neuropathy can evolve even after a single drug application. The recovery from symptoms is often incomplete and a long period of regeneration is required to restore function. Up to now, few drugs are available to reliably prevent or cure chemotherapy-induced neuropathy.
There continues to be a need for effective and potent PARP inhibitors which enhance the lethal effects of chemotherapeutic agents on tumor cells while producing minimal side-effects.
In addition, PARP inhibitors have been reported to be effective in radiosensitizing hypoxic tumor cells and effective in preventing tumor cells from recovering from potentially lethal damage of DNA after radiation therapy, presumably by their ability to prevent DNA repair. U.S. Pat. Nos. 5,032,617; 5,215,738; and 5,041,653.
Recent publications suggest that PARP inhibitors kill breast cancer cells that are deficient in breast cancer associated gene-1 and -2 (BRCA1/2). These studies suggest that PARP inhibitors may be effective for treating BRCA1/2-associated breast cancers. [Farmer et al., Nature 2005, 434, 917; DeSoto and Deng, Intl. J. Med. Sci. 2006, 3, 117; Bryant et al., Nature, 2005, 434, 913.]
There continues to be a need for effective and potent PARP inhibitors which enhance the lethal effects of ionizing radiation and/or chemotherapeutic agents on tumor cells, or inhibit the growth of cells having defects in the homologous recombination (HR) pathway of double-stranded DNA repair, while producing minimal side-effects.